$-\dfrac{5}{4} - \dfrac{4}{6} = {?}$
Solution: $ = - {\dfrac{5 \times 3}{4 \times 3}} - {\dfrac{4 \times 2}{6 \times 2}} $ $ = - {\dfrac{15}{12}} - {\dfrac{8}{12}} $ $ = - \dfrac{{15} - {8}}{12} $ $ = -\dfrac{23}{12}$